This invention relates to a process for preparing a product predominant in brominated pentaerythritols, which product has good color.
Brominated pentaerythritols are recognized as excellent flame retardants for use in polyurethane-based formulations. The most commercially significant brominated pentaerythritol is dibromoneopentyl glycol (DBNPG).
The commercial production of DBNPG is generally in accordance with the processes described in U.S. 3,932,541 and U.S. 4,154,966. The '541 process produces a product which is predominant in DBNPG, but which can contain significant amounts of monobromopentaerythritol and/or tribromoneopentyl alcohol. In distinction, the '966 is said to produce a product which is essentially pure (98%) DBNPG. The 2% balance of this product is assumed to be mono- and tribromo-homologs of pentaerythritol.
Whatever process is used to prepare the brominated pentaerythritol predominate products, the process preferably is designed to yield a product which is white or at least off-white. Products which are dark in color are not desired by formulators as the color can adversely affect the appearance of an article made from the polyurethane-based formulation.
It is, therefore, an object of this invention to provide a process for producing a brominated pentaerythritol product which has good color, which process is simple in execution and does not necessitate the use of anhydrous HBr.